I. Field of the Invention
This invention relates generally to medical apparatus used in a catheterization lab, and more particularly to a so-called "bail-out catheter" to be used in an emergency situation where the endothelial layer of a coronary blood vessel has been torn during the catheterization procedure and means must be provided for maintaining the blood vessel in a patent condition to prevent cell starvation distally of the injury site.
II. Background of the Invention
In angiography procedures where it is desired to visualize a portion of an organ such as the heart, a guide wire may first be introduced through a surgical opening in a vein or artery and then advanced through the vascular system to a desired location. Following that procedure, an angiographic catheter is advanced along the guide wire until its distal end is proximate a coronary ostium. Then the guidewire is withdrawn. Next, a radiopaque fluid is to be injected to render the site visible on a fluoroscopic screen.
In a somewhat similar fashion, when coronary transluminal angioplasty procedures are to be used to dilate a stenotic lesion, a balloon catheter is routed through the vascular system to the site of the lesion and then the balloon is inflated to spread or open the blood vessel at the site of the lesion.
In carrying out the above procedures, it can happen that the endothelial layer of the blood vessel in the coronary artery can be damaged to the point where the vessel collapses or such that a flap-like remnant can pull loose from the wall of the blood vessel and potentially occlude the blood vessel. Should such an episode occur, it is essential that patency be restored before downstream heart tissue is starved of its necessary oxygen. Advanced Catheter Systems, Inc. of Mountain View, Calif., offers a bail-out catheter in the form of an elongated plastic tube which is provided with a pattern of holes approximately 0.020 in diameter near the distal end thereof, the idea being that blood can flow through these apertures and beyond the site of the blood vessel damage. It has been found, however, that this commercially available bail-out catheter may become non-operational after relatively short periods of time due to clotting of the blood in the pattern of apertures.
It is the purpose of the present invention to provide an implement for maintaining vessel patency until surgical correction can be performed in the event that an angiography or angioplasty procedure has damaged a coronary blood vessel. The tool or utensil comprises an elongated wire helix having an outside diameter permitting it to be inserted through a guiding catheter, and an I.D. permitting it to be advanced over a guidewire. Over a majority of its length, the turns of the helix are tightly wound and abut one another, but at the distal end, the turns of the helix are open. Once the open turn portion of the implement are appropriately positioned so as to bridge the site of the damaged blood vessel, the guidewire can be removed while leaving the helical bail-out catheter of the present invention in place. Now, blood can readily flow over the surface of the bail-out catheter and when the open turns are reached, the blood may flow between those turns and through the center of the open helix past the point where the vessel may have collapsed against the bail-out catheter.